1. Field of the Invention
This invention is generally directed to control devices for controlling the operation of sprinkler or irrigation systems in direct response to the amount of rainfall which has occurred in the area of the sprinkler or irrigation system. More specifically, the present invention is directed to a control device for terminating the operation of a sprinkler or irrigation power supply system so as to prevent the further distribution of water through the sprinkler or irrigation system in response to a predetermined amount of rainfall being detected by the control device.
The control device of the present invention includes a receptacle in which fluid in the form of rain water is collected and wherein an electrical control switch is pivotally mounted so as to be operable by a float that is vertically movable within the receptacle in response to the accumulation of rain water therein. The switch of the present invention may be selectively vertically adjustably mounted within the receptacle so as to alter the operation of the switch to terminate the operation of the sprinkler or irrigation system depending upon a predetermined amount of rainfall which must occur before the irrigation or sprinkler system is no longer required. In addition, the control device includes structure for insuring that the electrical switch is not adversely effected by the accumulation of water within the receptacle and provides positive discharge outlets for preventing the accumulation of water beyond a predetermined volume. The control device also includes a cover and baffle for directing water relative to the electrical contacts of the control device and for preventing the accumulation of debris within the receptacle.
2. History of the Related Art
In many agricultural areas, it is often necessary to utilize some type of irrigation during the dry or hotter seasons. Many such irrigation or sprinkling systems are located in remote areas which are not easily monitored by or accessible to agricultural workers. Therefore, it is extremely important that some types of controls are provided to insure the proper operation of the sprinkling or irrigation system in the absence of any direct manual control and further to insure that such systems operate in the most efficient manner possible so as to conserve valuable water resources.
In many portions of the United States, subsurface deep well or aquifer water sources are being utilized to provide the necessary water to support proper crop growth during dry seasons or times of drought. Unfortunately, the necessary subsurface water reserves or aquifer levels often become dangerously low especially during elongated drought periods. In view of the foregoing, it is necessary to provide controls for irrigation and sprinkler systems in agricultural areas which will insure the most efficient use of water resources and which will prevent waste of water during those periods when natural rainfall is sufficient to support crop growth. Even in drought areas, sudden storms may result in significant quantities of rainfall over short periods of time. Although heavy rains often result in significant run-off which is not effective in providing the moisture to the soil to support plant growth, such storms do provide a significant amount of water which does penetrate the soil and should be accounted for in the overall watering requirements for any given crop.
In many older irrigation sprinkler systems, there was no provision for monitoring the amount of natural rainfall in order to control the amount of sprinkling or irrigating water introduced to given acreage or agricultural sites. Therefore, during those periods when sudden or unexpected storms deposited significant amounts of rain water to a given area, an excess of water was being simultaneously supplied by irrigation or sprinkler systems. Such a situation not only resulted in wasted water reserves but in some situations resulted in flooding of crops.
In view of the foregoing, there have been some prior art controls developed for sprinkling and irrigation systems which have been designed to account for natural rainfall in order to provide more efficient operation of sprinkler or irrigation systems. Unfortunately, systems developed to date have not provided the necessary reliance in control while being both economical and suitable for use in all agricultural areas. In U.S. Pat. No. 3,309,474 to Heinrich, a rainfall actuated switching apparatus is disclosed which includes a mechanically operated electrical switch which incorporates a lever mounted to a support post. One end of the lever is pivoted on one side of an axis into engagement with a push button electrical switch which makes or breaks electrical control to the motor of an irrigation or sprinkler system. A container is slideably mounted along the opposite side of the lever from the pivot point in which rain water may be received. Depending upon the placement of the container along the length of the lever, a different moment is established about the pivot point so that the weight of the water within the container may be utilized to force the first end of the lever into engagement with the electrical switch thereby effecting the control of the electrical circuit. Unfortunately, with such a system, a positive and accurate control of the electrical switch is not insured and the operation of the switch is not the same for each rainfall. Specifically, the harder the rainfall and the more dense the rain and wind during a given storm, the more quickly such an operating device would activate the switch. This is especially true if high wind gusts occur in the area which wind gusts would also serve to create pressure pushing on the container to aid in the engagement of the electrical switch by the operating lever. Further, debris in the air including fallen branches or leaves from agricultural crops can be retained within the container thereby offsetting its weight balance with respect to the electrical switch and, in some cases, causing an activation of the switch prematurely. In addition to the foregoing, such a mechanical relationship of the component parts will become less reliable over a given period of time due to the buildup of rust, dirt and other particles which will cause greater resistance of the electrical switch relative to the actuating lever and which will also result in binding of the pivot of the lever with respect to its support. Due to these shortcomings, such a control device is not suitable for use in providing an accurate and efficient control for terminating the operation of a sprinkling or irrigation system.
In U.S. Pat. No. 2,969,168 to Geiger, a misting control for cutting beds is disclosed which incorporates a lever type operating system utilizing a pivotable electrical switch. In this control device, an absorbent collector is mounted on one side of a lever and is counterbalanced by a weight on the opposite side thereof. An electrical switch is mounted along the lever and is tiltable depending upon the angle of the lever to either make or break an electrical contact to control the amount of spray being introduced to the cutting bed. As the absorbent material retains water or spray being introduced to the bed, the material will become heavier and offset the counterbalance weight. As with the structure discussed with respect to Heinrich, this type of lever balance system is not adequate for use in agricultural areas where the unit will be placed in an open field. Such a balancing type system will not be effective to regulate and accurately control the operation of the sprinkler system in response to a given amount of naturally occurring rainfall as the system is subject to being effected by debris, high wind gusts and humidity and evaporation conditions. The actuating lever may be activated or counterbalanced by tree limbs or leaves accumulatng on the absorbent material or by heavy rainfall in which the force of the falling rain is added to the quantity of rain being retained by the absorbent material. Further, in many areas where there are high humidity conditions, the absorbent pad may already retain a significant amount of moisture even though there may have been little rainfall. In view of the foregoing, such a system is not conducive for use in agricultural areas to insure that irrigation and sprinkling systems are only deactivated in response to given quantities of natural rainfall.
In U.S. Pat. No. 2,776,860, an electrical automatic sprinkling device is disclosed which utilizes a pair of solenoid operated switches which are mounted in line in vertically spaced relationship with respect to one another in a rain collector. Although this structure overcomes some of the shortcomings of the control devices discussed above, such a system is overly complex and does not provide all the safeguards which are believed necessary to insure an accurate and optimum control of an irrigation or sprinkling system in response to natural rainfall. Further, the sprinkling control device is utilized to both retain and monitor natural rain and rain being introduced through the sprinkling system. It is the purpose of the present invention to provide an automatic termination of a sprinkling or irrigation system in response to a given amount of naturally occurring rainfall. If the amount of moisture being introduced into the soil through the irrigation system is co-calculated with the amount of naturally given rainfall, then it would be necessary to subtract from the volume of liquid collected the exact amount of irrigation water being introduced to the crops to know exactly how much naturally occurring rain water had been collected within the control device. This is not the case with the present invention wherein only the naturally occurring rainfall is being monitored. Further, the device disclosed in Griffis includes an open conical receptor in which debris and other foreign materials may be collected and adversely effect the operation of the control device. Further, the collector is not designed so as to permit selective adjustment of the contact points within the collector so as to regulate the effective operation of the control circuit depending upon a wide range of amounts of natural rainfall.
Another type of rain detector for irrigation control systems is disclosed in U.S. Pat. No. 4,613,764 to Lobato. In this device, an open container or collection tray for receiving natural rainfall is provided adjacent a pair of electrical contacts which are positioned within the collection receptacle. The spaced electrical contacts or sensors are adjustable so that when a given amount of rainfall is collected within the tray, the sensors will complete a circuit to thereby control the irrigation system. With such a structure, the rain water being collected within the open tray is also subjected to the collection of debris which would give a false reading of the water volume. In addition, this type of control device subjects the controls of the irrigation system to intermittent open and closed circuit conditions especially as the level of the liquid within the collection tray approaches the sensor contacts. During a period of extremely heavy rainfall, it is possible that the contacts will make and break periodically as the rain water bridges the gap in the air space between the contacts and the liquid within the tray depending upon the liquid running from the tips of each of the contacts. In addition, high winds can cause rippling of the liquid contained within the tray which rippling can cause make and break electrical contacts. This situation could be damaging to electrical motors utilized in a sprinkler or irrigation system. It is further believed that in systems wherein there is direct electrical make/break developed by positioning electrical contacts within the rain water, that such contacts will break down or become rusted or deficient over a period of time due to the natural corrosive effect of the liquids with respect to the electrical contacts or sensors.
Another example of prior art rain or irrigation detector systems or sprinkler control includes U.S. Pat. No. 3,823,874 to Kroeck.